there is no 'hard' difficulty in the pc version, though you can emulate the wii's 'hard' difficulty setting by simply not collecting any of the life capsules.
Now, to reach the Hidden Last Cave and the Sacred Grounds...
- Jump over the gap where Prof. Booster falls in the Labyrinth so you don't have to get the Booster v0.8
- Examine the sparkling item on the bottom right of the room where you fight the Core either before fighting it (triggered by talking to Curly) or after beating it, before you run out of air
- Go into the building in the Waterway; rest on the bed; examine the computer; examine the right section of the bookshelf on the left of the room so you learn how to service flooded robots; "service" Curly; examine Curly over and over until you get the option to 'leave her here', pick "No"; complete the Waterway with Curly on your back until she falls off again after beating Ironhead
- Get to the Plantation, go to the bottom-right section; talk to the cthulhu; talk to Curly; talk to the cthulhu.
- Go back to the Mimiga Cemetary, fly up into the little hidden alcove, talk to Ma Pignon (the purple mushroom) and keep answering his questions until you get the Mushroom Badge
- Talk to him again, fight him, win, pick him up
- Take him back to Curly and 'stuff it in her mouth'
- Talk to her over and over until she gives you the Iron Band
- Make sure to talk to Momorin after the rocket's done before riding it so you trade your Mimiga Mask back for the Booster v2.0
Phew.. and that should do it.
